A hydroformylation reaction in which an olefin reacts with a synthesis gas(CO/H2) in the presence of a homogeneous organicmetaliic catalyst and a ligand to prepare linear (normal) and branched (iso) aldehyde having carbon atoms, the number of which is increased by one was originally discovered by Otto Roelen in Germany in 1938.
In general, the hydroformylation reaction that is known as an oxo react ion is a very important industrial reaction in views of a homogeneous system catalyst reaction, and about 8,400,000 tons of aldehydes including alcohol derivatives were produced by oxo reaction and consumed around the world in 2001 (SRI report, November 2002, 682. 700A).
Various types of aldehydes that are synthesized by the oxo reaction are converted into acids and alcohols that are aldehyde derivatives by using the oxidation process or the hydrogenation process. In addition, aldehydes can also be converted to long alkyl chain-containing acids or alcohols through aldol condensation and then oxidation or reduction.
In particular, hydrogenated alcohol of aldehyde, which is obtained by the oxo reaction, is called oxo alcohol. Oxo alcohol is industrially extensively used as a solvent, an additive, various types of raw materials of plasticizers, synthesis lubricants, and the like.
It is known that a metal carbonyl hydride compound has a catalytic activity of the hydroformylation reaction.
With respect to this, the industrially used catalyst is mainly cobalt (Co) or rhodium (Rh) series. The N/I (ratio of linear (normal) to branched (iso) isomers) selectivity of aldehydes varies according to the type of used catalyst, the type of used ligand and operating conditions.
Currently, in 70% or more oxo plants all over the world, even though there are disadvantages of the costly catalyst and a reduction in catalytic activity due to the poisoning, a low pressure oxo process using a rhodium catalyst and an excessive amount of phosphine ligand is adopted because of the high catalytic activity, the high N/I selectivity, and a relatively easy reaction condition.
In addition to cobalt (Co) and rhodium (Rh), a transit ion metal such as iridium (Ir), ruthenium (Ru), osmium (Os), platinum (Pt), palladium (Pd), iron (Fe), nickel (Ni) and the like may be used as the central metal of the catalyst for oxo reaction. However, in respects to the metals, it is known that the order of the catalytic activity is Rh>>Co>Ir, Ru>Os>Pt>Pd>Fe>Ni. Co, Rh, Pt, and Ru are metal belonging to Group VIII transition metal, and have a high catalytic activity to the oxo reaction. Pt and Ru are used only in a scholarly study, and a current commercial oxo process is based on rhodium and cobalt. Examples thereof may include HCo(CO)4, HCo(CO)3PBu3 and HRh(CO)(PR3)3.
Examples of the ligand that is used during the oxo process may include phosphine (PR3, R═C6H5, and n-C4H9) phosphine oxide, and phosphite Nitrogen-containing ligands such as amines, amides, or isonitriles have significantly lower catalytic activity as compared to the phosphorus-containing ligands due to their stronger coordination to the metal center. In particular, in the case of when rhodium is used as the central metal, there are few ligands superior to triphenylphosphine (TPP) considering catalytic activity, stability, and costs.
The Eastman Kodak Company and the Union Carbide Company (now, this company is bought by Dow, Co.) have developed a bidentate phosphine ligand and a bisphosphite ligand that have the high catalytic activity and the high N/I selectivity (U.S. Pat. No. 4,694,109, and U.S. Pat. No. 4,668,651). It is known that a bisphosphite ligand developed by the Dow Chemical Company has been used in some plants. Meanwhile, in the case of the poly-phosphite ligand that is represented by the ligand B in Examples 6 to 9 of U.S. Pat. No. 4,668,651, even though the ligand has the very high catalytic activity, the ligand shows very low N/I selectivity. Accordingly, it can be seen that the phosphite ligands have the significantly different catalytic activity and selectivity according to the structure thereof.
The diphosphine xantphos ligand that was developed by Kranenburg, et al, in 1995 is a ligand that is capable of increasing a bite angle between metal and phosphine (P-M-P) by 100° or more, and when the ligand is applied to the hydroformylation reaction, the selectivity to linear aldehyde can be increased, and studies regarding this have been continuously made.
As shown in Korean Patent Application No. 10-2004-73919, the present applicant developed a catalyst system in which a bidentate phosphorus compound containing nitrogen is applied to a transition metal catalyst which exhibits high catalytic activity and N/I selectivity in respects to the hydroformylation reaction.
Commercially, since the value of linear (normal) aldehyde is higher than that of iso aldehyde, there is a need to develop a technology of manufacturing a catalyst that has the excellent catalytic activity and the high N/I selectivity.